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JAMB Chemistry 1999 Question 17

Question 17

Volumetric Analysis

0.25 mole of hydrogen chloride was dissolved in distilled water and the volume made up to 0.50 dm3. If 15.00 cm3 of the solution requires 12.50 cm3 of aqueous sodium trioxocarbonate (IV) for neutralization, calculate the concentration of the alkaline solution

  1. A.0.30 mol dm−3
  2. B.0.40 mol dm−3
  3. C.0.50 mol dm−3
  4. D.0.60 mol dm−3.
Show the answer and explanation

Answer: A (0.30 mol dm−3)

Explanation

[HCl] = 0.25/0.50 = 0.50 mol dm−3, so 15.00 cm3 holds 0.0075 mol. Na2CO3 + 2HCl → 2NaCl + H2O + CO2, so Na2CO3 = 0.00375 mol in 0.0125 dm3 = 0.30 mol dm−3.